package com.jacobs.netty.websocketx.server;


import static io.netty.handler.codec.http.HttpMethod.GET;
import static io.netty.handler.codec.http.HttpResponseStatus.BAD_REQUEST;
import static io.netty.handler.codec.http.HttpResponseStatus.FORBIDDEN;
import static io.netty.handler.codec.http.HttpResponseStatus.NOT_FOUND;
import static io.netty.handler.codec.http.HttpResponseStatus.OK;
import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpRequest;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpHeaderNames;
import io.netty.handler.codec.http.HttpRequest;
import io.netty.handler.codec.http.HttpUtil;
import io.netty.handler.ssl.SslHandler;
import io.netty.util.CharsetUtil;

/**
 * Outputs index page content.
 */
public class WebSocketIndexPageHandler extends SimpleChannelInboundHandler<FullHttpRequest> {

  private final String websocketPath;


  public WebSocketIndexPageHandler(String websocketPath) {
    this.websocketPath = websocketPath;
  }

  @Override
  protected void channelRead0(ChannelHandlerContext ctx, FullHttpRequest req) throws Exception {
    // Handle a bad request.
    if (!req.decoderResult().isSuccess()) {
      sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, BAD_REQUEST));
      return;
    }

    // Allow only GET methods.
    if (req.method() != GET) {
      sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, FORBIDDEN));
      return;
    }

    // Send the index page
    if ("/".equals(req.uri()) || "/index.html".equals(req.uri())) {
      String webSocketLocation = getWebSocketLocation(ctx.pipeline(), req, websocketPath);
      ByteBuf content = WebSocketServerIndexPage.getContent(webSocketLocation);
      FullHttpResponse res = new DefaultFullHttpResponse(HTTP_1_1, OK, content);

      res.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/html; charset=UTF-8");
      HttpUtil.setContentLength(res, content.readableBytes());

      sendHttpResponse(ctx, req, res);
    } else {
      sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, NOT_FOUND));
    }
  }

  @Override
  public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
    cause.printStackTrace();
    ctx.close();
  }

  private static void sendHttpResponse(ChannelHandlerContext ctx, FullHttpRequest req,
      FullHttpResponse res) {
    // Generate an error page if response getStatus code is not OK (200).
    if (res.status().code() != 200) {
      ByteBuf buf = Unpooled.copiedBuffer(res.status().toString(), CharsetUtil.UTF_8);
      res.content().writeBytes(buf);
      buf.release();
      HttpUtil.setContentLength(res, res.content().readableBytes());
    }

    // Send the response and close the connection if necessary.
    ChannelFuture f = ctx.channel().writeAndFlush(res);
    if (!HttpUtil.isKeepAlive(req) || res.status().code() != 200) {
      f.addListener(ChannelFutureListener.CLOSE);
    }
  }

  private static String getWebSocketLocation(ChannelPipeline cp, HttpRequest req, String path) {
    String protocol = "ws";
    if (cp.get(SslHandler.class) != null) {
      // SSL in use so use Secure WebSockets
      protocol = "wss";
    }
    return protocol + "://" + req.headers().get(HttpHeaderNames.HOST) + path;
  }
}